The formation of Tribological Surface Transformation (TST), known as white etching layer (WEL) in the wheel–rail contact, corresponds to progressive and irreversible transformations on the surface of material due to the interaction of contact between two materials. The presence of WEL, damages the rails and cracks could initiate easily. Understanding the mechanisms of formation of WEL is important to prevent the problem of Rolling Contact Fatigue (RCF) in the rail network. The formation of the WEL is assumed to be due to a cyclic shear loading (at a high-frequency), under hydrostatic pressure associated with a moderate rise in temperature. Based on Transformed Induced Plasticity models and a previous model, a thermo-mechanical model taking into account the hydrostatic pressure, the shear stress and the temperature is presented to predict the formation of the WEL. An internal variable, representing all the steps of evolution of the microstructure leading to the WEL formation is introduced. 2-D finite element simulations of the rail running band (in the longitudinal direction) submitted to a cyclic thermomechanical loading are conducted to identify the model. The results are in good agreement with experimental observations for the size of the transformed zone after a given number of trains. The non-uniform repartition of WEL observed on the running band on trains could be explained by local variations of the thermomechanical loading. •A new thermomechanical model can predict theoretically the Tribological Surface Transformation.•The progressive formation of the White Etching Layer is modelled with an internal variable.•Dynamic variations of the wheel–rail contact conditions would catalyze the White etching layer formation.